Improvement Topic Update

# What is currently missing?

Currently when creating a Topic Update it is required to set the otherParams as the topicId.
This is not an intuitive way of storing the information and should be changed.

# How could this be improved?
The value should be stored or supplied in a way that makes sense and is easy and intuitave to understand when you read the code.
The method to update its self only supports one topic at a time but accepts a list of topics.
This should also be changed.

# Is this a feature you would work on yourself?

* [ ] I plan to open a pull request for this feature